Which step of the Lockheed Martin Cyber Kill Chain involves coupling an exploit with a backdoor into deliverable payload?

$1.$

Step $1-$ Reconnaissance $-$ This step of the Lockheed Martin Kill Chain involves coupling an exploit with a backdoor into deliverable payload.

$2.$

Step $2-$ Weaponization $-$ This step of the Lockheed Martin Kill Chain involves coupling an exploit with a backdoor into deliverable payload.

$3.$

Step $3-$ Delivery $-$ This step of the Lockheed Martin Kill Chain iinvolves coupling an exploit with a backdoor into deliverable payload $.$

$4.$

Step $4-$ Exploitation $-$ This step of the Lockheed Martin Kill Chain involves coupling an exploit with a backdoor into deliverable payload.